Graft Type, Not Tension, Determines ACL Tunnel Width

When you’re applying tension to a graft during an anterior cruciate ligament (ACL) reconstruction does that affect tunnel widening?

The recent study addressing this question, “Tibial tunnel widening following anterior cruciate ligament reconstruction: A retrospective seven-year study evaluating the effects of initial graft tensioning and graft selection,” appears in the December 2018 edition of The Knee.

Braden C. Fleming, Ph.D., the Lucy Lippitt Professor of Orthopedics, Professor of Engineering at the Warren Alpert Medical School of Brown University in Providence, Rhode Island and study co-author, explained his objective for the study to OTW, “We’ve been running a clinical trial looking at outcomes in response to two graft tensioning conditions. Tunnel widening is a known phenomenon after ACL reconstruction that is particularly common after reconstruction with ACL grafts. Because both graft types were included in the trial, we leveraged this database to determine if the tunnel widening was affected by the tension applied to the graft at the time of graft fixation.”

The study was based on, “Ninety patients, who were reconstructed with BTB [bone-patella tendon-bone] or HS [hamstring] autografts and were randomized using one of two initial graft tension protocols; 1) tensioned to restore normal anteroposterior laxity (n=46) and 2) tensioned to over-constrain anteroposterior (AP) laxity by two millimeters (n=44). Seventy patients had post-surgical data with 45 available for review at seven years…”

Dr. Fleming described the results OTW, “We determined that tunnel widening was dictated by graft type but not the initial graft tension. Patients who underwent ACL reconstruction with HS autograft had significantly more tunnel widening than those with bone patellar tendon bone autograft regardless of the initial graft tension condition.”

“The amount of tunnel widening that occurs post ACL reconstruction with a hamstring tendon graft was not affected by the amount of tension applied to the graft at the time of surgery. While there was a significant increase in tunnel widening using the hamstring tendon graft, the clinical outcome measures were not affected. The long-term implications of this remain unknown.”